This tutorial doesn't cover reasons why you might want to shoot with RAW and
stitch in 16bit format. It is a simple HOWTO listing the tools available and how
to use them with hugin.

Preparing the 16bit images

Start by using dcraw to read the RAW files and batch convert them into portable 16bit per
channel PPM files. RAW pictures from my Nikon 8700 have a .nef extension, so the
command looks something like this:

dcraw -v -w -4 dscn*.nef

Note that although hugin, nona and enblend support HDR floating-point data, there is no real loss
converting RAW data to 16bit colour depth as RAW images are typically only 12bit in the
first place. If you need a greater dynamic range than found in RAW images, it is possible
to combine bracketed exposures in a HDR workflow with hugin.

Note that I rotated them at the same time since these are portrait shots.
Gamma correction is also applied at this stage since RAW data is generally linear
and difficult to view without colour profile management (not yet supported by hugin).

Stitching with hugin

Information about the field of view was lost during the PPM stage, so this will need to be re-entered manually or re-optimised with PTOptimizer.

autopano-sift currently only supports 8bit per channel images, so if
you want to use this tool then you need to create temporary 8bit versions of each
image, generate control-points and then replace the images with the full version. Create
the 8bit files by adding -depth 8 to the convert command-line above.

Stitch the images as per usual into a TIFF file, you can use enblend as the
final step.

Post processing

This TIFF file is in 16bit per channel RGBA format, which is not viewable in most image
viewers or web-browsers, so there is an extra step to create portable images.
Open the file in a 16bit aware image editor such as cinepaint or krita, tweak the
colours, retouch or apply a contrast mask
and finally save in an 8bit per channel format such as JPEG.